Drifting inflatable with nobody on board

A shore-side witness reported a drifting red inflatable boat with no one on board. Police requested CGM to attend and determine circumstances. CRV Pelorus attended and located red dinghy with one diver on board. Intermittent engine problem but still operating. Diver had been gathering Kina and was well equiped for diving. However, near-gale SW winds and sea conditions were not ideal for an inflatable dinghy.